Proceedings Paper

The accuracy of image registration methods is dependent on peak sharpness which is dependent on scene content. As a result of characterizing joint scene content in terms of the joint probability density function, a new registration metric is defined as the thresholded difference (TD) method. It produces a sharper correlation peak than either the direct cross-correlation or mean absolute difference methods. Analytical comparisons and simulations are presented which show the TD method to exhibit less dependence on scene content than other pixel-by-pixel registration metrics. The method is easily normalized by a simple re-scaling of both images to the same range of gray levels. The thresholded difference registration metric is evaluated in terms of registering images which are incompatible due to additive noise, different spectral bands, temporal variations and scale differences. Simulation results show the TD method to be as good or better than other pixel-by-pixel correlation methods. An optimum threshold of half the image difference standard deviation at registration is indicated by simulation results. The TD method offers promise for enhanced registration accuracy for non-compatible images.